1. Field of the Invention
This invention relates to welding, and in particular to a welding electrode arrangement for use in producing closed-figure, for example annular, welds.
2. Description of the Prior Art
It is sometimes required to weld one member in a hole in another member, a weld being produced about the periphery of the hole thereby to seal the hole with the one member therein.
Such a requirement exists in the manufacture of sodium sulphur cells as described in GB-A-2161017. In such cells a central current collector in the form of a metal rod extends through a hole in a metal washer mounted on a `lid` of the cell, and it is necessary to weld the current collector in the hole in the washer to seal the hole.
Welding is effected by passing an electric current between the rod and the washer, and this is achieved by contacting the rod and the washer with mutually isolated electrodes connected to a source of welding current.